The invention relates to an agitating ball mill according to the preamble of claim 1.
Such agitating ball mills have a grinding chamber containing grinding media, a stator and a rotor, which are arranged in the grinding chamber, an input opening and an output opening for feeding and removing grinding material to or from the grinding chamber, as well as a grinding medium separation device arranged in the grinding chamber upstream from the output opening, which is used to separate grinding media entrained in the grinding material from the grinding material before the latter is removed from the grinding space through the output opening.
Agitating ball mills are used in the area of foodstuffs and in the manufacture of fine particles down to the nanometer range in size. Particles or agglomerates suspended in a liquid are here conveyed into the grinding chamber, and comminuted or dispersed in the grinding chamber by means of auxiliary grinding media before being conveyed out of the grinding chamber. To prevent the auxiliary grinding media from becoming dragged out of the agitating ball mill by the liquid stream of grinding material during this wet grinding process, resulting in the loss of the agitating ball mill and contamination of the grinding material, the auxiliary grinding media are held back in the grinding chamber by a separation device. A separating gap, grading screen or cellular wheel are used as separation devices. Essentially spherical elements made out of steel, glass, ceramic or plastic are used as the auxiliary grinding media.
In order to increase the mechanical grinding power introduced into the grinding material in the grinding chamber, the rotor and/or stator of known agitating ball mills is provided with pins that extend into the grinding chamber. As a result, impacts between the grinding material and the pins during operation directly contribute to the grinding power on the one hand. On the other hand, an indirect contribution to grinding power is made by impacts between the pins and the (auxiliary) grinding media entrained in the grinding material and subsequent impacts between the grinding material and grinding media. Finally, the shear and expansion forces acting on the grinding material also help comminute the suspended grinding material particles.